Pilot controlled valves

Abstract

A new pilot valve for spool-type valves and cartridge-type valves is disclosed. In both types of valve, the valve body (spool or cartridge) is provided with a cylindrical bore and first and second radial bores on opposite sides of a land on the valve body. The valve body is slidable within the axial bore of a valve housing. The valve housing is provided with a pressure inlet port, at least one service port, and usually at least one pressure return port, the ports being axially spaced apart. In a central position, a land of the valve body isolates the pressure inlet port from the pressure return port and/or the service port, one of the radial bores is in fluid communication with the pressure inlet port, and the other radial bore is in fluid communication with either a pressure return port or service port. A control rod is inserted in the cylindrical bore of the valve body and rotatable therein. The control rod is shaped to selectively open or close the radial bores to create a pressure imbalance across the valve body, thereby causing the valve body to shift in an axial direction. The control rod can be machined into different shapes to effect different degrees of control of the valve body movement (i.e. proportional versus directional control). The present invention is described for various types of spool valves and for a cartridge valve.

I claim: 
     
       1. For use in a valve housing having a first end with an opening and a second closed end, an axial bore extending between the first and second ends and a plurality of ports connected to the axial bore: a valve body that is laterally displaced within the axial bore by fluid pressure to open and close one or more ports, the valve body having two outer lands and at least one inner land, a first outer land being positioned adjacent to the first end of the valve housing and a second outer land being positioned adjacent to the second end of the valve housing, a cylindrical, lateral control bore extending the length of the valve body and being used to transmit both high and low pressure fluid for controliing the lateral displacement of the valve body, and first and second radial bores axially spaced apart between the two outer lands and coupled to the lateral control bore, and a controll rod extending through the opening in the first end of the valve housing, inserted in the lateral control bore and rotatable therein, the control rod having a passageway for both high and low pressure fluid that begins within the lateral control bore and extends to the end of the control rod nearest the second end of the valve housing, the passageway shaped so that in a first angular position the control rod covers both the first and second radial bores and neither radial bore is coupled to the passageway, in a second angular position the control rod uncovers the first radial bore, so that it is coupled to the passageway leading to the second end of the valve housing, and in a third angular position the control rod uncovers the second radial bore so that it is coupled to the passageway leading to the second end of the valve housing. 
     
     
       2. The invention of calim 1 further including means for preventing rotation of the valve body within the axial bore. 
     
     
       3. The invention of claim 1 wherein the valve body includes only one lateral bore. 
     
     
       4. A spool-type valve comprising: a valve housing having a first end with an opening, a second closed end, and an axial bore therebetween, a pressure inlet port, at least one pressure return port, and at least one service port, all the ports being connected to the axial bore at axially spaced positions;   a spool that is laterally displaced within the axial bore by fluid pressure, the spool having two outer lands and at least one intermediate land, a cylindrical, lateral control bore extending the length of the spool and being used to transmit both high and low pressure fluid for controlling the lateral displacement of the spool, and first and second radial bores located between the two outer lands and on opposite sides of an intermediate land, and coupled to the lateral control bore;   the housing ports axially spaced apart so that when the spool is in a first position within the axial bore the pressure inlet port is isolated from the pressure return port by a intermediate land, the service port is blocked by an intermediate land, the first radial bore is in fluid communication with the pressure inlet port, and the second radial bore is in fluid communication with a pressure return port; and   a control rod extending through the opening of the first end of the valve housing and inserted in the lateral control bore and rotatable therein, the control rod having a passageway that begins within the lateral control bore and extends to the end of the control rod nearest to the second end of the valve housing, the passageway being shaped so that in a first angular position the control rod covers both the first and second radial bores and neither radial bore is coupled to the passageway, in a second angular position the control rod uncovers the first radial bore, so that the first radial bore and pressure inlet port are coupled to the passageway, and in a third angular position the control rod uncovers the second radial bore, so that the second radial bore and the pressure return port are coupled to the passageway.   
     
     
       5. The invention of claim 4 further including means for preventing rotation of the spool within the axial bore. 
     
     
       6. The invention of claim 2 wherein the spool includes only one lateral bore. 
     
     
       7. The invention of claim 4 wherein the first and second radial bores are on immediate opposite sides of the intermediate land. 
     
     
       8. The invention of claim 4 further comprising a flexible coupling for the control rod, positioned between the spool and the first end of the housing. 
     
     
       9. A spool-type valve comprising: a valve housing having a first end with an opening and a closed second end connected by a bore extending therebetween, the bore having a first diameter portion adjacent, the first end and a second diameter portion adjacent the second end and adjoining the first diameter portion, the second dimeter being a different size than the first diameter;   a spool that is laterally displaced within the axial bore by fluid pressure, the spool having a control land closely received in the second diameter portion, two outer lands and two inner lands closely received in the first diameter portion, a cylindrical, lateral control bore extending the length of the spool and being used to transmit both high and low pressure fluid for controlling the lateral displacement of the spool, and first and second radial bores located between the two outer lands on immediate opposite sides of an inner land, and coupled to the lateral control bore;   the valve housing further having a pressure inlet port, first and second pressure return ports, and first and second service ports, all the ports communicating with the first diameter portion at axially spaced positions so that when the spool is in a first axial position one inner land isolates the pressure inlet port from the first pressure return port and blocks the first service port, the other inner land isolates the pressure inlet port from the second pressure return port and blocks the second service port, the first radial bore is in fluid communication with the pressure inlet port and the second radial bore is in fluid communication with the first pressure return port;   the valve housing also having a passage connecting the pressure inlet port to the second diameter portion on a first side of the control land; and   a cylindrical control rod extending through the opening of the first end of of the valve housing, inserted in the lateral control bore and rotatable therein, the control rod having a passageway that begins within the lateral control bore and extends to the end of the control rod nearest the second end of the valve housing, the passageway configured so that in a first angular position the control rod covers both the first and second radial bores and neither radial bore is coupled to the passageway, in a second angular position the control rod uncovers the first radial bore and couples it to the passageway, while covering the second radial bore, so that the pressure inlet port communicates with the second diameter portion of the valve housing on a second side of the control land, and in a third angular position the control rod uncovers the second radial bore and couples it to the passageway, while covering the first radial bore, so that the first pressure return port communicates with the second diameter portion of the valve housing on the second side of the control land.   
     
     
       10. The invention of claim 9 wherein the area of the first side of the control land is half the area of the second side of the control land. 
     
     
       11. The invention of claim 9 wherein the control rod has two faces cut at supplementary angles and spaced apart by a rod of smaller diameter so that a gap is created in the lateral control bore between the faces, and a channel connecting the gap to the second diameter portion on the second side of the control land, the gap and channel forming the passageway. 
     
     
       12. The invention of claim 9 wherein the valve housing passage includes a metering orifice. 
     
     
       13. The invention of claim 9 further including means for preventing rotation of the spool within the axial bore. 
     
     
       14. The invention of claim 9 wherein the spool inc1udes only one lateral bore. 
     
     
       15. A spool-type valve comprising: a valve housing having a first end with an opening and a closed second end connected by an axial bore extending therebetween, a pressure inlet port, a pressure return port, and a serivce port, all the ports communicating with the bore at axially spaced position;   a spool that is laterally displaced within the axial housing bore by fluid pressure, the spool having two outer lands and one inner land, a cylindrical, lateral control bore extending the length of the spool and being used to transmit both high and low pressure fluid for controlling the lateral displacement of the spool, and first and second radial bores located between the two outer lands on immediate opposite sides of the inner land and coupled to the lateral control bore;   the housing ports axially spaced apart so that when the spool is in a first axial position the inner land isolates the pressure inlet port from the pressure return port and blocks the service port, the first radial bore is in fluid communication with the pressure inlet port, and the second radial bore is in fluid communication with the pressure return port; and   a cylindrical control rod extending through the opening in the first end of the valve housing, inserted in the lateral control bore and rotatable therein, the control rod having a passageway that begins within the lateral control bore and extends to the end of the control rod nearest the second end of the valve housing, the passageway being configured so that in a first angular position the control rod covers both the first and second radial bores and neither radial bore is coupled to the passageway, in a second angular position the control rod uncovers the first radial bore, so that the first radial bore and the pressure inlet port are coupled to the passageway, and in third angular position the control rod uncovers the second radial bore, so that the second radial bore and the pressure return port are coupled to the passageway.